As part of a collaborative effort involving the National Cancer Institute, Santé publique France, the Francim network of cancer registries, and the Hospices Civils de Lyon, survival estimates for people with cancer in Réunion for the period 2008–2018 are being published for the first time. This work aligns with the objectives of the 2021–2030 Ten-Year Strategy for the Fight Against Cancer.

This study, based on data from the General Cancer Registry of Réunion, focuses on 10 of the most common cancer sites of regional interest. It presents estimates of 1-year and 5-year survival after diagnosis by age and sex using the same method as that applied to data from mainland France. These initial results reveal significant disparities among these cancer sites and differ from estimated survival rates in mainland France.

These data serve as a benchmark for survival in this department and provide essential information to support local health stakeholders in adapting regional versions of the Ten-Year Cancer Control Strategy and implementing Réunion’s 2023–2033 Regional Health Plan.

This report, along with a methodological note and supplementary materials, is available on the websites of the National Cancer Institute and Santé publique France.

Survival disparities¹ among the 10 cancer sites studied

For this first edition of survival data for people aged 15 and older with cancer in Réunion, the analysis focused on 10 of the most common cancer sites of regional interest. It covers individuals diagnosed with cancer in 2008 or between 2011 and 2015 and followed through June 30, 2018. The years 2009 and 2010 were excluded, as the data had not been validated at the time of the analysis.

The cancer sites studied are: the “lip-mouth-pharynx” group, the esophagus, the stomach, the “colon, rectum, and anus” group, the lung, the prostate, the breast, the body and cervix of the uterus, and “multiple myeloma and plasmacytoma.” For certain sites, due to insufficient sample sizes, survival estimates are sometimes presented for men and women combined or for one gender only.

These initial results show that survival varies significantly depending on the site studied and may, in some cases, differ from national estimates for mainland France. A comparison with mainland France, using a single value, does not reflect the disparities that exist between departments. Depending on the site, some departments may have survival rates identical to or even lower than those of the overseas territories.

As in mainland France, survival rates decline as the age at diagnosis increases for all the sites studied. For example, for cervical cancer, a woman diagnosed at age 50 has a 5-year net survival rate of 72%; this drops to 36% for a woman diagnosed at age 80. For cancers of the lip, mouth, and pharynx combined, the 5-year net survival rate drops from 52% at age 50 to 29% at age 80.

Health determinants and prevalence of chronic diseases: factors to consider in the fight against cancer in Réunion

Certain characteristics, specific to the territory and its inhabitants, may partly shed light on these results and the differences observed compared to the French mainland average⁵ without fully explaining them. Lower participation in organized cancer screening programs, more difficult access to care, a higher prevalence of certain chronic diseases, and a disadvantaged socioeconomic situation are all factors that can negatively impact population health.

Participation in organized screening programs needs to be improved, and diagnoses need to be made earlier

When focusing more specifically on cancer sites where 5-year survival rates are lower than the average for mainland France, several hypotheses can be proposed to explain these differences.

For cancers of the “lip-mouth-pharynx” group, the 5-year 5-year survival rate in Réunion (37%) is 8 percentage points lower for both sexes compared to the average observed in mainland ^France7 (45%). This discrepancy may be linked to a different distribution among the sub-locations within the lip-mouth-pharynx group, as the prognosis varies depending on the location.

It may also be linked to the proportion of cancers attributable to HPV infection, as HPV-related oropharyngeal cancers have a better prognosis than those attributable to alcohol or tobacco⁸. Furthermore, as observed in mainland France, excess mortality rates are highest at the time of diagnosis and increase with age. This can be explained by diagnoses at an advanced stage, the intensity of certain treatments, and the burden of comorbidities.

For breast cancer, the 5-year survival rate is 7 percentage points lower than the mainland ^France average9. In contrast, 5-year net survival rates by age show the same differences as in mainland France. They are significantly lower for women diagnosed at age 40 (84%) and 80 (71%) than for those diagnosed at ages 50 and 60, who have net survival rates of 89% and 90%, respectively. The differences observed compared to France are likely attributable in part to later diagnoses and associated comorbidities among older women. For those in the organized screening age group (50–74 years), one explanation may also lie in lower uptake of these recommended screening tests (51.4% participation in Réunion vs. 52.3% for all of France during the 2011–2012 period)¹⁰.

For prostate cancer, net survival decreases significantly for the oldest age groups at diagnosis (over 75 years). This may be explained by later diagnoses and/or the presence of age-related comorbidities that prevent optimal care. The practice of PSA screening (not recommended as a routine test), which is more widespread in mainland France than in Réunion¹¹, may partly explain the observed difference. While this screening allows for earlier diagnosis, it does lead to overdiagnosis of cancers with a favorable prognosis.

For cancers of the colon, rectum, and anus, which affect both women and men, the difference in 5-year survival rates compared to the French average¹² can be largely explained by excess mortality in the first few years following diagnosis, particularly among older patients and men. This may be due to later diagnoses and/or more significant associated comorbidities. Low participation in organized screening may thus account for part of the observed survival differences. Over the 2011–2012 period13, only 22.6% of eligible individuals in Réunion participated (vs. 31.5% for all of France over the same period).

For endometrial cancers, the 5-year overall survival rate is 7 percentage points lower than the mainland ^French average (67% vs. 74%). This survival gap with mainland France is particularly pronounced among women diagnosed at older ages. The more aggressive nature of this cancer, the more advanced stage at diagnosis due to less frequent gynecological follow-up among older women, the presence of comorbidities, and age-related difficulties in care are all prognostic factors that may explain the significant and early excess mortality from endometrial cancer among older women in Réunion.

Finally, an 8-point difference in the 5-year SNS is also observed for the “multiple myeloma and plasmacytoma” group between Réunion (52%) and the mainland France average15 (60%). It should be noted that, regardless of the region, 5-year survival decreases significantly with age at diagnosis. Thus, it is nearly double among those diagnosed at age 50 compared to those diagnosed at age 80, as the latter cannot undergo the most intensive treatments.

For cancers of the esophagus, stomach, and lung, the 5-year survival rates observed in Réunion are closer to the average observed in mainland ^France16. Five-year survival rates are lower the older the patient is at diagnosis, which may result from diagnoses at a more advanced stage, comorbidities (particularly those linked to tobacco and alcohol use for esophageal and lung cancers), and difficulties in care management due to the intensity of treatments.

Reunion generally has a good density of primary care practitioners, and the density of specialist physicians, across all organ specialties, is close to the French mainland average. However, there is a more pronounced shortage of specialists in oncology. Coupled with MRI and PET scanner availability rates below the national average for the period covered by the study, this underrepresentation may impact the time it takes for cancer patients in Réunion to receive care.

A high prevalence of certain chronic diseases

The prevalence of certain chronic diseases (chronic cardiorespiratory diseases, chronic kidney disease, diabetes, obesity, etc.) increases the risk of comorbidities that may reduce survival among people with cancer.
For example, in 2021, 13.6% of the adult population17 reported having diabetes, which is double the rate estimated in mainland France (Esteban study 2016).

Demographic and Socioeconomic Indicators

With 855,951 inhabitants as of January 1, 2018, Réunion has a relatively young population. Although its aging index more than doubled between 2000 and 2018, rising from 17 to 38 people aged 65 and older per 100 people under the age of 20, the latter group accounts for 30% of the population.

According to INSEE, in 2020, 36% of Réunion residents lived below the poverty line—2.5 times higher than in mainland France. One in two young households and one in two single-parent families are poor in Réunion. The unemployment rate there reached 21% compared to 8.4% in mainland France in 2019.

However, it has been observed that survival rates for people with cancer tend to be lower among those living in the most ^{disadvantaged} environments18. Many factors may explain this, such as difficulties accessing the healthcare system (screenings, early diagnosis, wait times, and access to certain treatment modalities), or patient characteristics (comorbidities, risky behaviors, psychosocial factors).

National and regional mobilization in cancer control policies

Isolated regions, including overseas territories, must be able to provide their residents with appropriate, high-quality healthcare. The ten-year cancer control strategy, in its fourth pillar “Ensuring that progress benefits everyone,” includes a specific measure for overseas territories.

This involves adapting cancer control initiatives, ensuring coordination among all stakeholders—particularly through digital technologies—supporting cooperation in overseas territories regarding prevention, care, and research, ensuring equitable access to care throughout the patient journey, and enhancing the attractiveness of these territories for healthcare professionals.
In this context, the National Cancer Institute, the Réunion Cancer Registry, and Santé publique France are working closely with the Regional Health Agency.

The ARS has implemented a regional adaptation of the ten-year strategy to tailor measures and actions to local specificities in order to better address the regional context.

The 2022–2025 regional roadmap reflects its strong commitment to the fight against cancer.

Implemented in partnership with cancer care stakeholders, it aims to reduce the impact of cancer on the health and lives of Réunion residents by addressing several challenges:

• making cancer risk prevention more accessible and improving screening;

• ensuring access to early diagnosis and to diagnostic and therapeutic innovations;

• coordinating patient care pathways;

• providing better support and guidance for patients and caregivers.

It is broken down into 35 operational objectives selected in consultation with all regional stakeholders.

Some actions carried out as part of this roadmap:

• In primary prevention, efforts to reduce the exposure of parents and young children to endocrine disruptors—initially implemented in three maternity wards—will be expanded to all seven maternity wards on the island by 2024, as part of the “First 1,000 Days” program. Some endocrine disruptors are classified as carcinogens, and others may indirectly increase the incidence of certain cancers by promoting risk factors such as obesity, cryptorchidism, or precocious puberty. Regional MRI and PET-CT capabilities have expanded, which should improve access to diagnosis and therapeutic follow-up for patients.

• In tertiary prevention, a third-place health facility will open in Saint-Pierre, designed to welcome and support the independence of patients with chronic diseases, including cancers, through specific Patient Therapeutic Education programs co-led by trained patient partners. This third-place facility will serve as an intermediate space between the home and traditional healthcare settings, and will contribute to the health education and information of patients and their caregivers.

Finally, during the Interministerial Committee on Overseas Territories meeting held on July 18, 2023, at Matignon, the Prime Minister announced a measure dedicated to oncology (Measure 25). This measure aims to:

"Reducing wait times for cancer care. The four most prevalent types of cancer in the overseas territories are colorectal, breast, cervical, and prostate cancers. For these four conditions, resources for prevention and early detection will be doubled in the overseas territories. For cancer patients, rapid access to care is a major challenge that justifies the implementation of cooperation between healthcare facilities to strengthen the existing healthcare infrastructure. An action plan will be finalized in early 2024 to significantly reduce wait times for cancer treatment."